测定室内空气中菌落总数时,采样器采样前,应对采样系统气密性进行检查,不得漏气。
参考答案:对
海豚、海豹、鲸、海狮等是生活在海洋中的哺乳动物,它们用______呼吸.
A distribution with a mean of 15 and a range of 2 to 25 would be:()
A. normally distributed.
B. positively skewed to the right.
C. cannot be determine.